“Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo” is a proper sentence.
1) Buffalo is a city near New York
2) buffalo is a verb meaning to bully
3) buffalo is an animal
Some punctuation improves understandability.
“Buffalo buffalo, Buffalo buffalo buffalo, buffalo Buffalo buffalo.”
That is, buffalo from Buffalo, buffaloed by other buffalo from Buffalo, also buffalo other buffalo from Buffalo.
It could have been bison, if “to bison” were a verb. The scientific name of Bison is “Bison bison bison”.
So… Bison bison bison Bison bison bison bison bison Bison bison bison.
Even better with badgers I guess? There is a town named Badger in Shropshire, in the UK, and also in Newfoundland. “To badger” means to bother, or to bug.
So… “Badger badger Badger badger badger badger Badger badger” would be a grammatically correct sentence.